1. Field of the Invention
The present invention relates to SiO2—Al2O3-based or Li2O—Al2O3—SiO2-based crystallized glass, and to a method for producing it. In particular, the invention relates to such crystallized glass that has wide-range applications as various precision parts severely required to have ultra-low expansion characteristics, ultra-surface-smoothness and high rigidity and that is favorable for various constitutive parts of next-generation semiconductor production devices, and relates to a method for producing it.
2. Background Art
SiO2—Al2O3-based or Li2O—Al2O3—SiO2-based crystallized glass may be made to have, for example, low-expansion characteristics (e.g., see Patent Reference 1, Patent Reference 2); and in addition, it has other useful physical properties intrinsic to crystallized glass of the type, such as high rigidity, and ultra-surface-smoothness after polished.
On the other hand, when SiO2—Al2O3-based or Li2O—Al2O3—SiO2-based crystallized glass is formed into large-size shaped articles, then it has some problems in that it may be often cracked or fractured in a step of thermal treatment of the precursor glass for crystal precipitation or in a step of crystal growth in the process of producing the glass articles; and the efficiency in production of large-size shaped articles of crystallized glass of the type is extremely low.
Patent Reference 3 discloses partially-crystallizing glass solder, of which the main crystal phase comprises a β-quartz mixed crystal phase. This reference says that the maximum value of an exothermic peak, the peak height and the peak area obtained in differential thermal analysis (DTA) give qualitative information relating to crystallization characteristics.
Patent Reference 4 discloses crystallized glass of which the main crystal phase is lithium disilicate, describing the profile of exothermic peaks observed in differential thermal analysis (DTA) and the stress occurring in crystallized glass.
However, these references do not concretely suggest anything about the type of profile of the exothermic peak curve of SiO2—Al2O3-based or Li2O—Al2O3—SiO2-based crystallized glass for solving the above-mentioned problems of cracking or fracture of the glass.    Patent Reference 1: JP-A-8-133783    Patent Reference 2: JP-A-2005-89272    Patent Reference 3: JP-A-59-174543    Patent Reference 4: JP-A-7-187710